A team of international astronomers, lead by the Instituto de Astrofísica de Canarias (IAC) in collaboration with the University of La Laguna (ULL) and other institutions, recently made a fascinating discovery. They found a dwarf galaxy that had remained invisible in previous sky surveys due to its faint surface brightness despite its considerable size. The galaxy has been named Nube, meaning “Cloud” in Spanish, which aptly reflects its ghostly and diffuse appearance.
This unique galaxy is challenging the current model of dark matter. Nube is ten times more extended yet ten times fainter than other dwarf galaxies with a similar number of stars. It’s about one-third the size of the Milky Way, but its mass is comparable to the Small Magellanic Cloud. The galaxy’s extreme characteristics have left astronomers puzzled, as with the current knowledge it is unknown how such a galaxy could exist.
Nube’s significant amount of dark matter is what sets it apart. It is an invisible substance that doesn’t emit, absorb or reflect light. Dark matter is undetectable by traditional telescopes, so its significant presence in Nube is remarkable. The dwarf galaxy’s discovery is significant because its faintness made it difficult to notice in previous sky surveys.
The discovery of Nube began with the analysis of a specific strip of sky by Ignacio Trujillo, the second author of the study. He noticed an intriguing faint patch that he further investigated using ultra-deep multicolor images from the Gran Telescopio Canarias. These images confirmed Nube’s existence, and future observations with the Very Large Array radiotelescope and the William Herschel Telescope are expected to provide more accurate distance measurements.
Nube’s discovery is akin to finding a hidden treasure in a well-explored attic. Its unique properties make this galaxy a fascinating subject of study. The galaxy’s extreme faintness makes determining its exact distance challenging, but initial estimates place Nube at about 300 million light-years away. The research team is confident that further observations of Nube will help them better understand the properties of dark matter and the formation of galaxies.
Study first author Mireia Montes, researcher at the IAC and the ULL, commented, “With our present knowledge, we do not understand how a galaxy with such extreme characteristics can exist,” highlighting the significance of their recent discovery. As research on Nube continues, there is no telling what other hidden treasures may be waiting to be uncovered.